The new Boris continuum 2020 (build version 13.0) is still incompatible with the POST part of Veges POST. This is the case with Vegas Post (build 321 and prior build) for both the latest Boris continuum 2019 (v.12) and the newer just released 2020 (v.13).

I have send tickets to both Vegas and Boris, they know the issue and are working on it (but my guess Boris priorities on that were not that high as they obviously were working on 2020 to push out I presume...).

Note that just using Boris 2019 (12.x) or the new Boris 2020 (13.0) in Vegas (without launching POST) still works OK.